The present invention relates to a hub for use in a magnetic recording tape cassette, and more particularly to an improvement to the means of stopping the end of the magnetic tape to the hub to be set in various kinds of magnetic tape cartridges.
According to general practice, the hub is provided with an engagement recess or a notch at a certain position on its outer peripheral surface, so that an end of the magnetic tape is inserted in said recess and then an elastically deformable plastic clamp piece is forced into said recess under partial deformation so as to engage the recess, and thus the end of the magnetic tape is stopped between the engagement recess and the clamp piece under pressure.
In the hubs having such a tape clamping structure it is usual for the end part of the clamp piece to be elastically deformed and set in pressure contact with the innermost part of the engagement recess in a slip-proof form, so that the elastic deformation of the end part of the piece is apt to affect to the outer surface of the piece. As a result, such drawbacks are induced that a change may occur to the curvature of the outer surface of the piece which was formed to have the same curvature as that of the outer peripheral surface of the hub, or a gap may be formed between the external surface of the piece and the outer peripheral surface of the hub, by which the hub as a whole may lose its true circle form, with the result that irregularities may be caused to the layer of the tape wound on the hub. In the case of the hub of a type in which the clamp piece is to be forcibly set into the engagement recess, an elastic deformation takes place also on the engagement recess, which causes a large gap between the clamp piece and the open edges of the engagement recess, thus giving rise to further increment of irregular winding of the tape.